The bike shop guy is partly correct - you can relieve pressure on your hands by changing the position of the bars... but you can change positions of drop bars the same way. Generally speaking, you have at least three discrete hand positions on drop bars that can be set up similar to the position of flat bars - the bar tops, the 'shoulders' and the hoods. Furthermore, bikes designed for drop bars often have shorter top tubes, so the closest and highest position (the bar tops) can possibly be higher and closer than the single position on a flat bar. Add that position to the nearby shoulders and hoods and you can rotate through three upright positions with completely different shapes under you r hands. Thent here are the drops and the flats (ends of the bars below the drops) and you can change you hand and body position as mucha s you like to avoid fatigue.
HOWEVER
My experience is that the bars are only one piece of the puzzle... saddle position is often a culprit in putting too much pressure on your hands.